1. Field of the Invention
The present invention relates generally to spindle motors for use in disk drives, and more particularly to a spindle motor having a spindle motor stator with laminate layers for increased head stack assembly access.
2. Description of the Prior Art
The typical hard disk drive includes a disk drive base, and a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to the disk drive base. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA) that includes at least one transducer head, typically several, for reading and writing data to and from the disk. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to tracks disposed upon the disk.
The head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional xe2x80x9crotaryxe2x80x9d or xe2x80x9cswing-typexe2x80x9d actuator assembly typically comprises an actuator body that rotates on a pivot assembly between limited positions, a coil portion that extends from one side of the actuator body to interact with one or more permanent magnets to form a voice coil motor, and one or more actuator arms which that extend from an opposite side of the actuator body. A head gimbal assembly includes at least one transducer head, sometimes two, which is distally attached to each of the actuator arms. The actuator assembly includes the actuator body that has a bore and a pivot bearing cartridge engaged within the bore. The at least one head gimbal assembly and the flex circuit cable assembly are attached to the actuator assembly.
The spindle motor includes a hub that is rotatably attached to the disk drive base. The hub has an outer flange that supports one of the disks. Additional disks may be stacked and separated with spacers. The spindle motor further includes an annular magnet and a spindle motor stator. Where space efficiency is of vital concern, the magnet is typically attached about the lowermost portion of the hub below the flange. The magnet consists of a predetermined number of N and S poles that are disposed alternately circumferentially about the magnet. The spindle motor stator includes an outer rim that is attached to the disk drive base and a plurality of internally facing stator teeth. The stator teeth are equally spaced and extend from the stator rim. The spindle motor stator is sized to fit about the hub and in particular the magnet. Each stator tooth includes windings which selectively conduct current to create a magnetic field that interacts with the various poles of the magnet. Such interaction results in forces applied to the hub which tend to rotate the hub. In those disk drives capable of reading both sides of the disks, the head stack assembly includes an actuator arm that extends and pivots between the vertical region between the lowermost disk and the spindle motor stator. A magnetic shield is provided between the head stack assembly in such region over the stator teeth for protecting against magnetic flux interacting with the magnetic data on the disk and the head stack assembly.
A topic of concern is the desire to reduce the overall disk drive size. Such disk drives may have a variety of applications such as in hand held or portable electronic devices. The exterior size and shape of the disk drive is often referred to as a xe2x80x9cform factorxe2x80x9d. Reduction of such disk drive form factor has proven challenging. This is because the mere reduction of the size of the various disk drive components may result in such components being unable to conform to required specifications and standard form factors for such components, and may result in installation or assembly difficulties.
One particular area of focus is the reduction of the height of the disk drive. As mentioned above, a prior art arrangement includes a lower actuator arm which extends and pivots between the vertical region between the lowermost disk and the spindle motor stator. Such prior arrangement is contemplated to be a limited factor in the overall sizing of the disk drive height. Accordingly, there is a need in the art for an improved spindle motor configuration in comparison to the prior art.
An aspect of the invention can be regarded as a spindle motor for use in a disk drive having a rotatable head stack assembly. The spindle motor has a spindle motor hub. The spindle motor further has a magnet radially attached about the spindle motor hub. The spindle motor further has a spindle motor stator. The spindle motor stator has a stator rim. The spindle motor stator further has a plurality of stator teeth arrayed about and internally extending from the stator rim. The stator teeth are sized to fit about the magnet in operable communication therewith for rotating the spindle motor hub. The stator teeth have laminate layers. The stator teeth have at least one reduced height stator tooth. The reduced height stator tooth has fewer laminate layers than a remainder of the stator teeth. The reduced height stator tooth is positionable adjacent the head stack assembly for allowing the head stack assembly to pivot over the reduced height stator tooth.
The reduced height stator tooth may have a width greater than a remainder of the stator teeth. The reduced height stator tooth may have a tooth body portion and a distal shoe extending from the tooth body portion. The shoe is disposed adjacent the magnet. Further, the distal shoe may extend vertically beyond the tooth body portion.
According to another aspect of the present invention, there is provided a spindle motor for use in a disk drive having a rotatable head stack assembly. The spindle motor has a spindle motor hub. The spindle motor further has a magnet radially attached about the spindle motor hub. The spindle motor further has a spindle motor stator. The spindle motor stator has a stator rim formed of at least two vertically stacked stator rim laminate layers. The spindle motor stator further has a plurality of stator teeth arrayed about and internally extending from the stator rim. The stator teeth are sized to fit about the magnet in operable communication therewith for rotating the spindle motor hub. The stator teeth are each formed of at least two stator tooth laminate layers. The stator tooth laminate layers are respectively attached to the stator rim laminate layers. The spindle motor stator further has at least one reduced height stator tooth having at least two reduced height stator tooth laminate layers horizontally off-set from and vertically formed towards each other. The reduced height stator tooth being is adjacent the head stack assembly for allowing the head stack assembly to pivot over the reduced height stator tooth.
In addition, the at least two reduced height stator tooth laminate layers may include an upper laminate layer and a lower laminate layer. The upper and lower laminate layers may be horizontally off-set from each other. In another embodiment, the at least one reduced height stator tooth laminate layers include an upper laminate layer, a lower laminate layer, and an inner laminate layer between the upper and lower laminate layers. The upper and lower laminate layers are horizontally off-set from the inner laminate layer. According to another embodiment, the at least two reduced height stator tooth laminate layers include an upper laminate layer and a lower laminate layer. The lower laminate layer extends horizontally from the stator rim and the upper laminate layer is formed towards the lower laminate layer. Further, in another embodiment of the stator motor, all of the stator teeth may take the form of the above described reduced height stator tooth.
According to another aspect of the present invention, there is provided a spindle motor for use in a disk drive having a rotatable head stack assembly. The spindle motor has a spindle motor hub. The spindle motor further has a magnet radially attached about the spindle motor hub. The spindle motor further has a spindle motor stator. The spindle motor stator has a stator rim formed of at least two vertically stacked stator rim laminate layers. The spindle motor stator further has a plurality of stator teeth arrayed about and internally extending from the stator rim. The stator teeth are sized to fit about the magnet in operable communication therewith for rotating the spindle motor hub. The stator teeth have laminate layers formed to a first thickness. The stator teeth have at least one reduced height stator tooth. The reduced height stator tooth has laminate layers formed to a second thickness less than the first thickness. The reduced height stator tooth is positionable adjacent the head stack assembly for allowing the head stack assembly to pivot over the reduced height stator tooth. Further, the reduced height stator tooth may have a width greater than a remainder of the stator teeth.
In additional embodiments of the present invention, there are provided disk drives each having a disk drive base and a head stack assembly. The above-mentioned stator motors may be included the disk drives.